Groups III-V nitride semiconductors have been extensively used as main materials for light emitting devices, such as a light emitting diode (LED) or a laser diode (LD), due to the physical and chemical characteristics thereof In general, the groups III-V nitride semiconductors include a semiconductor material having a composition formula of InxAlyGa1-x-yN (0≦x≦1, 0≦y≦1, and 0≦x+y≦1).
The LED is a semiconductor device, which transmits/receives signals by converting an electric signal into infrared ray or light using the characteristics of compound semiconductors. The LED is also used as a light source.
The LED or LD using the nitride semiconductor material is mainly used for the light emitting device to provide the light. For instance, the LED or the LD is used as a light source for various products, such as a keypad light emitting part of a cellular phone, an electric signboard, and a lighting device.